Vintage Heuer with missing serial numbers?

Hello,

Wondering if you can help me. I bought a vintage 1974 Heuer Montreal (cal 12) last year and recently had it serviced at Tag Heuer in Switzerland. I noticed on the Tag Heuer service receipt said reference number N/A and when tried to look for a serial number/reference number on the side of case, I could not find any. The caseback also does not have a serial number!

Trying to figure out if my watch is authentic/altered or maybe some vintage Heuer watches weren’t stamped with serial numbers?

Thanks

Which ref Montreal are we talking about?
I’m not familiar with the third gen but 1st and 2nd should have the numbers between the lugs. Might have been worn due to bracelet but most often these have been polished away during case refurbishment.

Ref 110.503 BC

That one should have the numbers engraved between the lugs. Actually not between the lugs but slightly above the lugs. Therefore these numbers are polished out very often when the case if refurbished. Shuck The Oyster has one for sale that is unpolished, you can see both numbers. For sale here.
Priced correctly at 5.5k I think, it's a dealer also, as 99/100 Montreals you find for sale will have lots of wear or have been refurbished. Original, collector grade Montreals are very rare. I have the earlier generation 110.503n with applied markers, also unpolished, and with both numbers visible.
Depending on what you paid I wouldn't be too worried in any case. I have seen plenty of refurbished Montreals without the numbers being sold at high prices.

Thank you! Yes, the case was probably refurbished and serial numbers polished out. The case looks spectacular (satin brush on top with polish on side) but someone probably accidentally removed the serial number in doing so- who knows!!
Either way, I love the watch- very unique look and feel and a throw back to the 70’s!

I'm a fan of the Montreal too. Can we see a pic of this glorious beast soon?